An information recording and/or reproducing apparatus apparatus is known which uses an optical information storage disk as a medium for recording and/or reproducing sound and/or image information. An information recording and/or reproducing apparatus using such an information storage medium has various predominant advantages over apparatus using magnetic information recording and/or reproducing media such as floppy disks and hard disks. One of such advantages is the far higher information storage density available of an optical information storage disk. An optical information recording and/or reproducing apparatus is however unsatisfactory in respect of the access time required in reading and/or writing information on the information storage medium. This drawback results principally from the requirement for moving the optical information record/pickup head assembly which consists of a bulky, heavy-weight focusing unit including an object lens, a reflector mirror and a focusing actuator. In the case of a magnetic disk recording and/or reproducing apparatus, a magnetic head which is far smaller in size and lighter in weight is to be driven for movement in reading and/or writing information on the information storage medium.